What Joe mentioned, elision, is certainly a critical point in learning to sing anything at all fast in Spanish. More often than not in Spanish when two vowels come together (even if there's a word boundary between them) they will be sung as a single syllable, and often one of the vowels will essentially disappear. I don't know much Spanish, and I don't know this song, haven't ever heard it to my knowledge, but looking at your text I would say for the following portion the underlined parts are likely to be treated as single syllables:

Ta empezando lo velorio
Que le hacemo a Babalu
Dame diez y siete velas
Pa ponerle en cruz.
Dame un cabo de tabaco mayenye
Y un jarrito de aguardiente,
Dame un poco de dinero mayenye
Pa' que me de la suerte.

My wife and I rode with my niece who grew up in Mexico and now lives in Guatemala to visit a cousin/aunt and back early last week, and we sang some Spanish stuff (mainly hymns), and listening to her, the tendency for one vowel to completely disappear was much more marked than it would be if I sang the same text, which probably just means I would "sing with an American accent".